Air compressor for internal-combustion engines



July 10, 1928; 1,677,057

A. B. STREETER 1 AIR COMPRESSOR FOR INTERNAL COMBUSTION ENGINES Filed March 1925 2 Sheets-Sheet I dig}.

INVENTOR atgmwmm ATTORNEY July 10, 1928.

A. B. STREETER AIR cournnssoa FOR INTERNAL comsuswxou ENGINES Filed larch 1925 2 Sheets-Sheet 2 N lNVENTdR ATTORNEY Patented July 10, 1928.

UNITED TSTATES Isms? PATENT, OFFICE.

. ALBERT a. sraasran, or New YORK, N. Y-, assreuoa' ro DUAL MOTORS coaroaa- 'rron, or NEW YORK, 11. 1., a ooaroaxrron or nnmwm.

m COMPRESSOR FOR INTERNAL-COMBUSTION ENGINES.

Application filed mm a, 1m. serials. 12,990.

Inthe accompanying drawings Fig. 1 is a view in vertical axial section taken throu h one of a pair of cylinders forming a d uplex unit constituting a pre- .ferred embodiment of the invention and taken on the line 11 of Figure 2, looking in the direction indicated by the arrows;

Fi res 2 and 3 are each horizontal sectiona views through the engine casing and taken respectively on the lines 22 and 3-3 of Figure 1 and Fig. 2 shows the reservoir cover removed. V g

-In the following description and in the claims, parts will be identified by specific names for convenience of expression but they are intended to be as generic in their application to similar parts as the art will permit. In the drawings there is shown an engine block 10 and which in the present instance is designed as a unit to include two parallel cylindrical constructions. Each construction includes an upper explosion chamber 11 and a lower pump cylinder 12. A differential area piston 13 is contained in each of the cylinder structures. These cylinders are similar so that a detailed description of one will apply equally to the other. The small head 14 of the piston works in the explosion chamber 11 and the large head 15 works in the pump cylinder to form in each case an air com ressor. The upper end of the block is close by a head 16 preferably formed as asingle unit casting to fit over the top of both explosion cylinders and at the top of each explosion chamber is a spark plug 17. Each explosion chamber is provided at its lower endwith a series of exhaust ports 18 circumferentially spaced about one side of the cylinder. A line of air scavengin lnlet rts 19 are oppositely disposed to t e exh ust ports.

The invention relates in general to an 1nternal combustion engine of the t e in which the smaller end of a differentla piston moves in an explosion chamber and the larger end moves in a pump chamber to form an air compressor and in which air under pressure from an air compressor is dischar ed in the explosion, chamber for scavenging the same of its refuse gas, and the invention relates s cifically to an 1mproved form of two-cyc e engine of the t pc in which air from the compressor is a ditionall'y' utilized to feed fuel to'the combus- 66 tion cylinder.

.finally blast the fuel charge into the com- The present disclosure more particularly relates to the part of such an engine when functioning as an air compressor when generatmg, storing and dispensing compressed air for use as a scavenging medium and for use in supplying combustion supporting air to the associated explosion cylinder. This disclosure constitutes a companion case with my co-pend'ing applicationentitled Fuel intake for two-cycle engines{, Serial No. 13,671 filed March 7, 1925.

In two-cycle engines of the type herein disclosed it has been known to force air under pressure from the pump chamber through long restricted passageways into the explosion chamber for the urpose of scavenging the same of its re se gases. Such known forms, however, have featured the'blowing of a jet of air usually under'extremely high pressure into the combustion chamber to effect; the scavenging act. The present disclosure, on the contrar features the scavenging of the explosion c amber by utilizing air under relatively low pressure but in large volumetric "amounts to insure a thorough and comparatively slow evacuation of the refuse gases from the cylinder.

The primary object of the invention is to provide in an engine of the type disclosed, a simplified means for economically generating and utilizing the compressed air necessary for scavenging and combustion supportingpurposes, in such way that the energy consumed bythe compressor piston will be kept at a minimum and distributed to do useful work in producing at the proper time the pressure and volume required to efficiently scavenge the cylinder and supply the necessary combustion supporting air and bustion cylinder.

Another object of the invention is to provide a simplified form of valvular control for regulating the timed sequence of the passage of air 1n the performance of its several functions and to insure the proper differential in the directing of air at that pressure best suited for its scavenging and combustion supporting functions.

Another object of the invention is to provide a simplified form of engine castln'g, which will be compact and of small all-over dimensions-compared withthe power developed, which will contain a low pressure air reservoirv of relatively large capacity and in 110 which the reservoir and the valvular 1nechanism controlling the air so ply, is readily accessible for inspection an repair.

Various other objects and advantages of the invention will be in part obvious from an inspection of the accompanying drawings and in part will be more fully set forth in the following particular description of one form of mechanism embodying my invention, and the invention also consists in cer tain new and novel features of construction and combination of parts hereinafter set forth and claimed.

Extending across the lower portion of the explosion cylinders and just above the pump cylinder 12 is a. long open top recess forming a low pressure air reservoir 20. This reservoir opens directly into both of the explosion cylinders through the scavenging air inlet ports 19. This reservoir 20 is closed by means of a long cover 50 by the removal of which ready access is attained to the reservoir, to the inlet ports 19 and to an air control valve hereinafter described.

The bottom of the reservoir 20 is formed of a lon cylindrical valve casting 40 provided with three circumferentially spaced ports. An upper port 51 opens directly into the reservoir 20, a laterally extending port 52 opens directly into the pump cylinder 12 and a lower port 53 constitutes an air inlet port and opens directly from the external atmos here. A long cylindrical rod 39 is rotata 1y mounted in the casing 40. This rod is cut away at two points to form a diametrical plate valve 54 rotatable about the axis of the shaft and located to pass the line of orts 51, 52, and 53 at the upper ends of bot air compressors.

This valve rod is also provided with a pair of diametrically extending passageways 41 for placing the upper end of the pump cylinder in fluid communication through passageways 45, 43 and 42 with a pipe 38 leading to an associated fuel metering device 29 for supplying the explosion chamber through a fuel port 24, as is more fully described in my copending application above identified.

Projecting from the upper end 23 of the piston is a aflle 46 which in so far as this disclosure is concerned functions to direct the scavenging air towards the closed upper end of the combustion chamber and prevents a direct discharge across the top of the piston through the exhaust ports.

In operation it will be understood that the device operates as is usual with two-cycle internal combustion engines now in general use. Assuming that the previous charge has been fired and that the piston has moved to the limit of its movement on its working stroke, it will be understood that the upper end 23 of the piston uncovers the scavenging air inlets and exhaust ports thus opening the cylinders to the scavenging effect of low pressure air which flows from the reservoir 20 into the explosion chamber and therefrom discharges through the exhaust ports as is usual in such devices. The operation of the air controllin rotary valve 54 is so timed that the valve 18 closin communication between the reservoir an both the external atmosphere and the pump cylinder during the tune that the reservoir is discharging into the explosion chamber. During the period when the large head of the piston, functioning as an air compressor piston, is moving into its limiting position on its compression stroke the low pressure reservoir is cut off from the air compressor so that the air under maximum pressure is directed solely to the fuel metering device and none of this high ressure air is consumed in the gentler wor of scavenging the explosion chamber.

By means of this construction it is possible to maintain the reservoir sup lied economically with a large volume 0 air under relatively low pressure, but at such pressure as will insure a thorough scavenging of the explosion cylinder and leave the cylinder filled with air in volumetric amount substantially sufiicient to support the succeeding combustion act. By means of an organization of elements such as is herein disclosed it is possible to design the parts so that there will be supplied to the air reservoir from the alternate action of the two air compressors a supply of air substantially at uniform pressure and nicely balanced with reference to the demands made by the engine during a long eriod of operation and under variable con itions of load such as is required of an engine when constituting the prime mover of an automotive vw hicle. As the engine changes its speed it will at the same time proportionately change its air supply and the reservoir is of sufiicient capacity to compensate for the normal variations in air supply necessary to clear the cylinders at different engine speeds.

In the device disclosed the air supplied to the metering device is independent of the supply utilized for scavenging purposes and for the initial charging of the combustion chamber with its-combustion supporting air. It is only the air produced at final compression which is utilized in the fuel system and all the other air is discharged into the reservoir.

\Vhile 1 have shown and described, and have pointed out in the annexed claims, certain novel features of my invention, it will be understood that various omissions, substitutions and changes in the form and de; tails of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

Hill

the external atmosphere, the second opening into the pump chamber and the third dpening into the reservoir, and a rotary blade valve mounted in said valve casin for periodically opening the pump chaniber to the external atmosphere and to the reservoir.

2. In an internal combustion engine, the combination of an explosion cylinder having an air scavenging port, an axially aligned cylinder of larger diam'eterthan the explosion cylinder, a trunk piston having two heads one working in each cylinderand forming in the larger cylinder an annular pump chamber, an air reservoir constantly open to the airscavenging port, acylindrical rotar valve casing having three circumferentialy spaced openings, one an air intake opening directly to the external atmosphere, the second opening into the pump chamber and the third opening into the reservoir, the head of the piston in the pump chamber acting towards the endof its compression stroke to close the second opening, arotary valve mounted in said valvecasing for periodically opening the pump chamber to the external atmosphere and to the reservoir, said reservoir having a capacity substantially equal to the volumetric capacity of the pump chamber, and a rotary valve for alternately controlling the admission of external air to the pump chamber and for opening the pump chamber to the reservoir.

3. In an internal combustion engine, the combination of a plurality of cylinder units each including a combustionv chamber, a fuel intake, a pump cylinder, and a piston with one head working in the combustion chamber and the other head working in the pump cylinder, a valve casing, extending across said units and provided with a plurality of ports, one for each pump cylinder and opening into the same and one for each combustion chamber and opening into the same through its associated fuel intake, a single valve shaft mounted for rotary movement in said valve casing and provided opposite each of said ports with a valve element for controlling its associated ort, a single air reservoir common to bot units provided with a plurality of'air discharging ports one for each combustion chamber and open-r pressure air I reservoir supplied from the pump cylinder and open to the scavenging port, and a single rotary valve construction for controlling the passage of low pressure air to the reservoir'and for controlling the passage of high pressure air to said fuel metering valve.

5. In an internal combustion engine, the combination of an air pump cylinder provided with two outlets and a piston working in said cylinder, one. outlet disposed adjacent the end of the vpiston stroke and the other being in spaced relation thereto and closed by the movement of the piston past the same, a single rotary valve rod having a pair of openings extending therethrough and disposed in alignment with said outlets, and said opening isposed in timed relation to the piston to cause the outlet at the end of the piston stroke to be open as the pistonapproaches said end of its stroke.

6. In an internal combustion engine, the

combination of a combustible cylinder, a pump cylinder anda piston Working in both cylinders, said combustion cylinder pro vided with a fuel inlet port and an air scavenging port, a high pressure air conduit leading from thepump cylinder to the fuel inlet port, a low pressure air reservoir supplied from the pump cylinder and open to the scavenging port, and a single rotary valve construction for controlling the passage of low pressure air to the reservoir and for controlling the passage of high pressure air to said fuel metering valve. 7

7.- In an internal combustion engine, the combination of a combustible cyllnder, a

'pump cylinder and a piston working in both cylinders, said combustion cylinder provided with a fuel inlet port and an air scavenging port, an air conduit leading from the pump cylinder to the fuel inlet port, a conduit leading from the pump cylinder to the scavenging port and a single valve operatively controlled to open the pump cylinder to the fuel inlet port and to the scavenging port.

8. In a device of the class described, the combination of a' pump cylinder, a piston working in the cylinder, said cylinder provided in spaced relation to the end of the.

piston travel on its'compression stroke with a low pressure air outlet passageway, a low Ill pressure air reservoir supplied therfrom, a

rotary valve for controlling the'passageway' between the pump cylinder and said reservoir, a fuel metering device and a high pressure air passageway leading from the pump chamber at the end of the piston stroke to said device and a rotary valve in said passageway operable in timed sequence with the.

bustion chamber, arranged in close prox imity to one end of the latter, a passageway for leading low pressure air from the pumping chamber to the air intake port, a fuel mixture. intake port arranged in one side of the combustion chamber-intermediate the length of the latter, said piston functioning to close all of said orts, a second passageway for leading higi pressure air from the pumping chamber to the fuel mixture intake port, means for introducing fuel into the last mentioned passageway, and valve means interposed in said passageways and adapted during the first portion of the compression stroke of the piston to close the secondpassageway and open the first passageway, and later, during the compression stroke of the piston, to close the first passageway and open the second passageway.

10. In an internal combustion engine, the combination of a combustion cylinder having an exhaust port, and an air scavenging port at one end and a fuel inlet port spaced longitudinally of the cylinder from said exhaust and scavenging ports, a pump cylinder, a differential area piston having its smaller area movable in the combustion chamber and controlling the ports thereof, and its larger area piston moving in the pump cylinder to form an air compressor, a conduit leading from the compressor to the scavenging port, a rotary valve controlling said conduit, another conduit separate from the first named conduit leading directly from the air compressor to the fuel inlet port, and a fuel metering device in said other conduit.

11. In an internal combustion engine, the combination with a plurality of cylinder units each including a combustion chamber, a pump cylinder and a piston with one head working in the combustion chamber and another working in the pump cylinder, of a single combined valve casing and low pressure air reservoir extending across said units, said reservoir provided with scavenging ports opening into the several combustion chambers, said valve casing provided with ports for lacing the same in communication with t e several pump cylinders and for placing the same in communication with the single air reservoir, a high pressure air conduit leading from said pump cylinder, 11 single valve in'said valve casing for controlling the air flow through its ports and through said conduit, and means for introducing fuel to said conduit without passing the fuel through the pump chambers.

Signed at New York, in the county of New York and State of New York, this 13th day of February A. D. 1925.

ALBERT B. STREETER. 

